The relationship between the renin-angiotension-aldosterone system and the sympathetic nervous system is being explored in electrolyte abnormalities. We have reported that epinephrine infusions in physiological amounts result in rapid movement of K from plasma to intracellular fluid. These observations have stimulated an attempt to study the possibility that changes in plasma catecholamines may be correlated with serum K abnormalities in patients with hypo and hyperkalemia.